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Liquid Oxygen/Liquid Methane Test Results of the RS-18 Lunar Ascent Engine at Simulated Altitude Conditions at NASA White Sands Test FacilityTests were conducted with the RS-18 rocket engine using liquid oxygen (LO2) and liquid methane (LCH4) propellants under simulated altitude conditions at NASA Johnson Space Center White Sands Test Facility (WSTF). This project is part of NASA's Propulsion and Cryogenics Advanced Development (PCAD) project. "Green" propellants, such as LO2/LCH4, offer savings in both performance and safety over equivalently sized hypergolic propulsion systems in spacecraft applications such as ascent engines or service module engines. Altitude simulation was achieved using the WSTF Large Altitude Simulation System, which provided altitude conditions equivalent up to ~122,000 ft (~37 km). For specific impulse calculations, engine thrust and propellant mass flow rates were measured. LO2 flow ranged from 5.9 - 9.5 lbm/sec (2.7 - 4.3 kg/sec), and LCH4 flow varied from 3.0 - 4.4 lbm/sec (1.4 - 2.0 kg/sec) during the RS-18 hot-fire test series. Propellant flow rate was measured using a coriolis mass-flow meter and compared with a serial turbine-style flow meter. Results showed a significant performance measurement difference during ignition startup due to two-phase flow effects. Subsequent cold-flow testing demonstrated that the propellant manifolds must be adequately flushed in order for the coriolis flow meters to give accurate data. The coriolis flow meters were later shown to provide accurate steady-state data, but the turbine flow meter data should be used in transient phases of operation. Thrust was measured using three load cells in parallel, which also provides the capability to calculate thrust vector alignment. Ignition was demonstrated using a gaseous oxygen/methane spark torch igniter. Test objectives for the RS-18 project are 1) conduct a shakedown of the test stand for LO2/methane lunar ascent engines, 2) obtain vacuum ignition data for the torch and pyrotechnic igniters, and 3) obtain nozzle kinetics data to anchor two-dimensional kinetics codes. All of these objectives were met with the RS-18 data and additional testing data from subsequent LO2/methane test programs in 2009 which included the first simulated-altitude pyrotechnic ignition demonstration of LO2/methane.
Document ID
20090026004
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Melcher, John C., IV (NASA Johnson Space Center Houston, TX, United States)
Allred, Jennifer K. (NASA White Sands Test Facility NM, United States)
Date Acquired
August 24, 2013
Publication Date
August 2, 2009
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-CN-18473
Meeting Information
Meeting: 45th AIAA/ASME/SAE/ASEE Joint Propulsion
Location: Denver, CO
Country: United States
Start Date: August 2, 2009
End Date: August 5, 2009
Sponsors: American Society of Mechanical Engineers, American Inst. of Aeronautics and Astronautics, Society of Automotive Engineers, Inc., American Society for Electrical Engineers
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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